JPH11228298A - Growth of compound semiconductor crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crystal-growing method for growing a bulk crystal by introducing a gaseous feedstock by which a bulk crystal of a compound semiconductor is enabled to be grown by preventing generation of a crystal nucleus and controlling the deterioration of homology of the growing interface. SOLUTION: This method growing a compound semiconductor crystal at a low temperature part of a growing room by a vapor phase method comprises forming an exterior room to be filled with a first gaseous feedstock including at least one of the constituent element of the compound semiconductor, connecting the exterior room to a growing room through a gaseous feedstock introducing hole, arranging a solid raw material or a liquid feedstock including the remaining elements of the constituent elements of the compound semiconductor in the growing room or the exterior room at the neighbor of the gaseous feedstock introdsucing hole, forming a second gaseous feedstock from the solid feedstock or the liquid feedstock, allowing the first gaseous feedstock and the second gaseous feedstock to diffuse to a low temperature part of the growing room by the difference of the partial pressure to crystallize the compound semiconductor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for growing a compound semiconductor crystal by a gas phase method using a solid or liquid source and a gas source.

[0002]

2. Description of the Related Art Bulk crystal growth of a compound semiconductor by a vapor phase method generally involves disposing a polycrystalline raw material in a high-temperature portion of an ampoule and sublimating the raw material or reacting it with a transport medium to generate a gaseous raw material. It is intended to transport by diffusion and / or convection to a low-temperature portion in the ampoule and re-solidify in the low-temperature portion to obtain a single crystal. II-VI group compound semiconductor crystals such as ZnSe, CdTe, ZnS, and CdS are widely manufactured by the above method. In these methods, a gaseous raw material is generated from a solid raw material arranged in an ampoule and used.

In contrast to the above method, a crystal growth method in which a part of the gaseous raw material is supplied from outside the growth chamber is chloride V
It is widely used for growing a compound semiconductor thin film, such as a PE method, a hydride VPE method, and a MOVPE method. When a bulk crystal is grown by these methods, for example, when trying to grow a bulk crystal having a thickness of 1 cm or more, crystal nuclei are generated on the surface of a holder or the like holding a seed crystal, and polycrystallization is performed from that portion. proceed. In addition, the homogeneity of the growth interface is deteriorated, and a macro step is formed. As a result, voids are generated in the crystal.
Therefore, the crystal growth method in which a part of the gaseous raw material is supplied from the outside cannot be applied to the growth of the bulk crystal.

[0004]

SUMMARY OF THE INVENTION The present invention is directed to a method for solving the above-mentioned problems and for growing a bulk crystal by introducing a gaseous raw material. An object of the present invention is to provide a crystal growth method capable of growing a compound semiconductor bulk crystal by suppressing deterioration.

[0005]

According to the present invention, in a vapor phase growth method for introducing a gaseous source, energy for transferring a gaseous source in a growth chamber to a growth region is diffused under static pressure without using forced convection. This makes it possible to prevent the above-mentioned generation of crystal nuclei and suppress the deterioration of homology at the growth interface, thereby enabling the growth of bulk crystals.

The configuration of the present invention is as follows. (1) In a method for growing a compound semiconductor crystal in a low temperature part of a growth chamber by a vapor phase method, an outer chamber filled with a first gas source containing at least one of the constituent elements of the compound semiconductor is provided. And the growth chamber are connected via a gas source introduction hole, and in the growth chamber or the outer chamber, in the vicinity of the gas source introduction hole, a solid source containing the remaining element of the compound semiconductor or A liquid source is disposed, a second gas source is generated from the solid source or the liquid source, and is diffused in a low temperature part of the growth chamber by a partial pressure difference between the first gas source and the second gas source, and a compound semiconductor is formed. A method for growing a compound semiconductor crystal, characterized by crystallizing.

(2) A first gaseous raw material is introduced into the outer chamber,
The compound semiconductor crystal according to (1), wherein the concentration of the first gaseous material in the outer chamber is always kept constant by discharging excess first gaseous material from the outer chamber. Method.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a conventional vapor phase growth method such as a chloride VPE method, when growing a bulk crystal while partially supplying a gaseous material from the outside, the gaseous material is supplied to the seed crystal side by forced convection. Therefore, large supersaturation is formed in the vicinity of the seed crystal, and in-plane unevenness in the supply rate of the gaseous raw material in the seed crystal plane is inevitable. As a result, large supersaturation in the vicinity of the seed crystal causes nucleation in portions other than on the seed crystal to precipitate polycrystals, and in-plane non-uniformity in the supply rate causes in-plane non-uniformity in the growth rate.
If the above growth is performed, a macro step is formed at the growth interface.

Therefore, in the growth of a bulk crystal by a vapor phase method, crystal growth cannot be performed stably if there is gas convection. Therefore, not only forced convection but also suppression of natural convection has been an important issue. Therefore, when growing a bulk crystal while supplying a part of the gaseous material from the outside,
Both forced convection and natural convection must be minimized. Various methods have been proposed for suppressing natural convection, but simple methods such as reducing the inner diameter of the growth chamber and reducing the internal pressure of the growth chamber are simple methods.

[0010] The most important problem here is to suppress forced convection. This is because when a bulk crystal is grown while a part of the gaseous raw material is supplied from the outside, forced convection necessarily exists. Therefore, in the present invention, an outer chamber is provided before the growth chamber, and the first chamber is filled with a first gaseous raw material containing at least one of the constituent elements of the compound semiconductor, and the outer chamber is connected to the growth chamber. In the vicinity of the gas source introduction hole, a solid source or a liquid source containing the remaining elements of the compound semiconductor is arranged, and a second gas source is generated from the solid source or the liquid source. The first gas source and the second gas source are diffused under static pressure in the portion, and the compound semiconductor is crystallized, so that forced convection is limited to the outer chamber,
Forced convection in the growth chamber could be suppressed, and bulk crystal growth became possible.

In this method as well, the growth stops when the gaseous raw material component in the outer chamber is exhausted. Therefore, it is desirable to introduce the gaseous raw material into the outer chamber along with the crystal growth. In the case where a gas other than the gaseous raw material is formed during crystal growth, the gas is discharged from the outer chamber and the partial pressure of each gas in the outer chamber and the growth chamber is kept constant, so that crystal growth is performed. It is possible to continue under the same conditions for a long time. Here, the gas introduced into the outer chamber is not limited to the gas raw material. That is, a gas that mediates the reaction or transport or an inert gas for adjusting the pressure may be simultaneously introduced.

FIGS. 1 and 2 are conceptual diagrams of a growth apparatus for carrying out the method of the present invention. The growth apparatus shown in FIG. 1 has a growth chamber disposed in an outer chamber, an inlet and an outlet for a first gaseous material are provided in the outer chamber, and a seed crystal is disposed in a low-temperature portion at one end of the growth chamber. The other end is provided with, for example, a gaseous material introduction hole in the form of a mesh so that it can communicate with the outer chamber. Then, a solid or liquid source is placed near the gas source introduction hole in the growth chamber,
A solid or liquid source is heated by a heater disposed around the growth chamber to generate a second gas source, and the first gas source and the second gas source are transferred to a low temperature part of the growth chamber under static pressure. To grow a crystal on a seed crystal. As described above, since the transfer of the gaseous raw material is performed under static pressure without using forced convection, a supersaturated state is not formed in the vicinity of the seed crystal, and in-plane nonuniformity of the growth rate is avoided. It becomes possible. The solid or liquid raw material can be disposed in the outer chamber in the vicinity of the gas raw material introduction hole. However, part of the second gas raw material generated from the solid or liquid raw material is discharged from the outer chamber to the outside of the system. There is a disadvantage that it is done.

The growth apparatus shown in FIG. 2 communicates the outer chamber with the growth chamber through a gas material introduction hole, and a gas material outlet is provided in the outer chamber immediately before the gas material introduction hole. FIG.
This is a device having the same structure as that of FIG. 1, and is used in the same manner as the device of FIG. The crystal growth method of the present invention can be applied to any type of crystal growth as long as an appropriate reaction system is present. It is also effective for growing a group III-V compound semiconductor crystal that is nitrogen.

[0014]

(Embodiment 1) GaAs was grown using the growth apparatus shown in FIG.
An s crystal was grown. N ₂ and AsC from the gas feed inlet
l ₃ mixed gas was introduced into the outer chamber at a rate of 2 sccm, and the gas was exhausted from the gas raw material outlet so that the inner pressure of the outer chamber became 5 torr. A single-sealed quartz tube having an inner diameter of 25.4 mm and a depth of 50 mm was used as a growth chamber, and a quartz lattice was attached to the open end side. A quartz boat containing Ga was placed near the quartz lattice in the growth chamber. On one side of the growth chamber, a (111) B-plane GaAs substrate having a diameter of 1 inch was disposed as a seed crystal. The part where Ga is placed is 900
℃, the temperature of the seed crystal portion was heated to 800 ℃, crystal growth was carried out for 30 days. The obtained crystal was a GaAs single crystal having a thickness of 14 mm and having a (111) B facet.
When the (111) B facet was visually observed, macro steps were not observed, stable facets were formed, and the thickness of the crystal was uniform. When the crystal was sliced, no void was observed in the cross section.

[0015]

According to the present invention, there is provided a compound semiconductor having a stable facet surface containing no void by a vapor phase growth method using a solid or liquid raw material and a gas raw material by adopting the above structure. Enabled the growth of bulk single crystals.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a crystal growth apparatus for performing a method of the present invention.

FIG. 2 is a conceptual diagram of another crystal growth apparatus for performing the method of the present invention.

Claims (2)

[Claims] 1. A method for growing a compound semiconductor crystal in a low temperature portion of a growth chamber by a vapor phase method, wherein an outer chamber filled with a first gas source containing at least one of the constituent elements of the compound semiconductor is provided. An outer chamber and the growth chamber are connected via a gas material introduction hole, and a solid containing the remaining elements of the compound semiconductor in the vicinity of the gas material introduction hole in the growth chamber or the outer chamber. Disposing a raw material or a liquid raw material, generating a second gaseous raw material from the solid raw material or the liquid raw material, and diffusing the second gaseous raw material in a low temperature part of the growth chamber by a partial pressure difference between the first gaseous raw material and the second gaseous raw material; A method for growing a compound semiconductor crystal, comprising crystallizing a semiconductor. 2. A method of introducing a first gaseous raw material into the outer chamber and discharging an excess of the first gaseous raw material from the outer chamber so that the concentration of the first gaseous raw material in the outer chamber is always constant. 2. The method for growing a compound semiconductor crystal according to claim 1, wherein the crystal is held.